Deep water mobile marine platform



Feb. 7, 1961 G. E. SUDEROW 2,970,446

DEEP WATER MOBILE MARINE PLATFORM 2 Sheets-Sheet 1 Filed May 15, 1956 wwysl ti INVENTOR IF AI GEORGE asubenow fifl ATTORNEYS Feb. 7, 1961 G. E. SUDEROW 2,970,446

DEEP WATER MOBILE MARINE PLATFORM Filed May 15, 1956 2 Sheets-Sheet 2 FIG.4.

/ 3 2 INVENTOR 24/4M GEORGE E. SUDEROW BYWMW ATTORNEYS United States Patent DEEP. WATER MOBILE MARINE PLATFORM George E. Suderow, New York, N.Y., assignor to De Long Corporation, New York, N.Y., a corporation of Delaware Filed May 15, 1956, Ser. No. 585,021

3 Claims. (Cl. 61-46.5)

This invention relates to mobile marine platforms that can be supported above water at offshore sites on marine-bottom-engageable legs. More particularly, this invention relates to mobile marine platforms that can be erected in deep water.

Mobile marine platforms of the type under consideration are known, and such platforms are presently in use in the Gulf of Mexico, and at other offshore locations, for drilling for oil. Platforms presently in use, however, can be erected only in marine locations of relatively shallow water depths, e.g., of the order of 50 to 60 feet. The legs used to support such present day platforms usually are in the form of tubular steel caissons of a maximum size of the order of about 6 feet in diameter. Such mobile platforms have operated satisfactorily in the relatively shallow water depths previously mentioned, but it will be seen that at greater depths, the supporting legs must be of increased length. This gives rise to strength problems in the supporting legs because of the relatively long, unsupported length thereof extending between the elevated platform and the marine bottom. The strength of tubular steel caissons can, of course, be increased by making the caissons of larger diameter or of increased wall thickness. Larger diameters or increased wall thickness, however, result in tremendous increases in weight, and consequently, in the difficulty of manipulating such legs. Furthermore, an increase in the diameter of steel caissons would result in an increase in the area acted upon by waves with a resulting undesirable increase in wave forces acting upon a mobile marine platform of the type under consideration when such platform is erected.

The aforedescribed disadvantages attendant the use of tubular steel caissons as legs for supporting marine platforms of the type under consideration in deep water, can be overcome by using openwork structural towers as such supporting legs. Openwork structural towers not only combine structural strength with lightness in weight, but also present a relatively small area which will be acted upon by waves, with a resulting decrease in the wave forces on an erected platform. Structural steel towers, however, still present problems of manipulation because of their large size. For example, a structural steel tower adapted to be used as a supporting leg for a marine platform in water depths of the order of 300 feet may be of the order of 380 feet in length or height and about 30 feet square in cross section, if a tower that is square in cross section is used. By means of this invention, however, openwork structural towers of the afo-redescribed size can be used as the supporting legs of mobile marine platforms of the type under consideration, and such towers can be manipulated by means of power-operated mechanisms presently in use on platforms having tubular steel caissons as their supporting legs.

Hence, it is an object of this invention to, provide a mobile marine platform of the type under consider? "ice ation with means for facilitating the erection thereof in deep water on a plurality of openwork towers.

It is another object of this invention to provide a mobile marine platform of the type under consideration which utilizes known power-operated devices for raising the platform on openwork towers used as supporting legs.

Other objects and advantages of the invention will become evident from the following description and drawings in which:

Figure l is an elevational view of a mobile, deep water marine platform embodying this invention and showing the platform in condition to be towed from one marine site to another;

Figure 2 is a view corresponding to Figure 1, but illustrating a step in the erection of the platform at a marine site;

Figure 3 is a view corresponding to Figure 1, but showing the platform erected at a marine site;

Figure 4 is an enlarged plan view, partly in section, of the platform shown in Figure 1, and taken substantially on lines 2-2' of such figure;

Figure 5 is an enlarged, fragmentary plan view of an element shown in Figure 3 and illustrating constructional details;

Figure 6 is a sectional view taken on lines 66 of Figure 5.

Referring now to the drawings, there is shown therein a mobile marine structure or platform embodying this invention and including a buoyant body or hull 10 which may be generally rectangular in plan view and is adapted to be towed from one marine location to another. If the platform is intended to be used for drilling for oil or the like, at offshore marine sites, the hull 10 may be of the order of about 200 feet in length and feet in width, and have a deck 12 providing a relatively large open area on which drilling equipment (not shown) and accessories can be mounted.

At each corner of the hull 10 a guiding well 14 extends vertically'therethrough and mounted in each well for vertical movement relative to the hull is an openwork structural tower 16. In the particular embodiment illustrated in the drawings, the towers are substantially square in cross section so that the'guiding wells 14 are likewise square in plan view. For use at marine sites having water depths of the order of 300 feet, the towers 16 may have an overall height of the order of 380 feet so that the marine platform can be erected and supported out of the watervwell above wave action at such sites, as later describedf The bottom or lower end portion of each tower 16 is constituted by an appropriately internally braced, hollow, waterand air-tight tank 18 (Figures 2 and 3) that essentiallyconstitutes an extension of the openwork portion of the tower. Secured to the underside of each tank 18 is an appropriate matting or reinforcing structure 20 to prevent puncture of the tank by any irregular or sharp objects on the marine bottom, when the towers 16 are lowered into engagement with the latter as later explained. Appropriate piping or hose connections (not shown) lead from each tank 18 to suitable water pumps and air compressors (not shown) mounted in or on the hull 10, so that the tanks can be controllably flooded or have the water therein displaced by air to control the buoyancy of the tanks to any desired degree. Preferably, the tanks 18 have a sufficient maximum buoyancy to float the towers 16 in the upright position shown in Figure 1, that is, wherein the bottoms of the tanks 18 are substantially flush with the underside of the hull 10 to minimize towing resistance of the entire structure i and the towers are held upright in such position by the guide wells 14. In this connection it will be seen that even though the towers 16 extend to a relatively great height above water when in towing position, because of their openwork construction with resulting lightness of weight as compared to the hull 10, and because-of the broad base provided by the latter, theentire structure will be stable and can be towed safely from one marine site to another.

At two opposite diagonal corners of each tower-guiding well 14, the hull 10 is provided with vertically extending caisson-guiding wells 22. The caisson wells 22 are circular in cross section and spaced somewhat away rom the corresponding corners of the tower wells 14. In the embodiment illustrated, the caisson wells 22 may be of the order of 6 feet 1 inch in diameter to slidably receive and guide tubular steel caissons 24 having an outer diameter of 6 feet. The tubular steel caissons 24, which constitute supporting members as later described, may be of the order of 80 to 100 feet in height or length for use in a structure of the particular magnitude previously described.

Operable on each caisson 24 and secured to the hull 10 adjacent the corresponding caisson well 22 is a poweroperated jacking mechanism 26 that is engageable with its corresponding caisson to forcefully effect relative vertical movement between the latter and the hull. Such jacking mechanisms 26 may be of the type disclosed more in detail in the copending application of Pointer, Serial No. 283,567. Appropriate controls (not shown) are provided on the hull 10 for operating the jacking mechanisms individually or simultaneously.

Secured to and extending diagonally across the top of each tower 16 is a beam 28 having the opposite ends thereof projecting over the upper ends of the corresponding pa r of caissons 24. As is bestshown in Figures and 6, the projecting ends of the beams 28, which may be channel-shaped in cross section, can be detachably secured to the upper ends of the corresponding pair of caissons 24, so that vertical loads imposed upon the caissons by the jacking mechanisms 26 can be transmitted to the correspondingtowers 16. For this purpose, a disc 34} may be suitably secured, as by welding, in the upper end of each caisson 24 and reinforced by crossed,

backing, stiffener plates 32 that are welded to both the disc and the caisson. Secured to and extending upwardly from the disc 30 are a plurality of threaded studs 34 adapted to extend through oversize holes 36 in the web of the beam 28. When the studs 34 are received in the holes36, a reinforcing plate 38, apertured to receive the studs, is placed over the studs to rest on the web,and secured in place by nuts 40 threaded onto the studs.

In operation of a mobile marine platform embodying this invention, the tanks 18 at the foot of each tower 16 are rendered buoyant so that the towers will float in the position shown in Figure 1, wherein the bottoms of the tanks are substantially flush with the undersurface of the hull 10, and will be retained upright in such position by the tower wells 14 in the hull. Also, the jacking mechanisms 26 are operated to elevate the caissons 24 so that their lower ends are substantially flush with the bottom of the hull 10. Consequently, it will be seen that the entire structure including the hull 10, the towers 16, and the caissons 24, can be towed to a predetermined erection site. When an erection site is reached, the buoyancy of the tanks 18 is controllably decreased, by controllably flooding the same, to'slowly sink the towers 16 until they engage or substantially engage with the marine bottom at the site, as shown in Figure 2. Depending upon the exact water depth at the site, the relative length of the towers 16 and caissons 24, and the vertical positions of the latter relative to the hull 10, the projecting ends of the beam 28 of a particular tower will engage the upper ends of the corresponding pair of caissons before the tower engages the marine bottom, or else the. tower will hit-bottom before the projectingends ofthe beam engage the upper ends of the caissons. In the latter event the caissons 24 are raised by their jacking mechanisms 26 until they engage the beam 28. In either event, when the beam 28 engages the upper ends of the caissons 24, the plate 38 and nuts 40 are installed to connect the beam to the caissons. Ifthe connection is made while a tower 16 is off the marine bottom, the jacking mechanisms 26,013 the corresponding pair of caissons'24 are operated to lower their caissons as the tower is sunk to the marine bottom;

After the towers 16 have been engaged with the marine} bottom and all of the caissons 24 have been connected to their respective beams 28, all of the jacking mecha nisms 26 are operated simultaneously to raise the'hull= It on the caissons 24, as is shown in Figure 3, until the bottom of the hull is above wave action. This distance between the bottom of the hull 10 and mean water level normally will be about 40 feet. It will be seen that the tension loads imposed on the caissons 24 in carrying. the .weight of the hull 10 will be transmitted to the beams 28, and thence to the towers 16, so that the entire weight of the hull 1t] and the equipment carried thereon will be stably supported by the towers. In the event that the jacking mechanisms 26 are of the type described in the aforementioned Pointer application, wedging devices, for example, of the general type disclosed in the copending application of Suderow, Serial No. 382,948, now Patent No. 2,873,580, may be employed to support the hull 10 on the caissons 24 independently of the jacking mechanisms so that the motors (not shown) utilized in developing fluid pressure for operating the jacking mechanisms can be shut down. It will be seen that the hull 10 will thereupon provide a fixed and stable marine platform from which well drilling operations or the like can be effectively and safely conducted.

When drilling operations or the like have been com-- pleted and it is desired to move the platform and erect the same at another marine site, the following sequence of operations is performed. First of all, the jacking mechanisms 26 are rendered operative to engage their corresponding caissons 24 and support the weight of the hull 10 while any wedging devices which may have been used to supportthe hull on the caissons independently of the jacking mechanisms are released. Thereupon, allof the jacking mechanisms 26 are operated simultaneously to lower the hull 10 back down on the caissons 24 until the hullbecomes afloat. At this time, the nuts 40 and plates 38 connecting the upper ends of the caissons 24 to their corresponding beams 28 are disengaged, while thecaissonsare supported by their jacking mechanisms 26,,so that the towers 16 will be free to move vertically in their, wells 14 independently of the caissons. The towerbuoyancy tanks 18 then are controllably rendered buoyant to slowly float the towers 16 back up into the position shown in Figure 1, i.e., wherein the bottoms of the towers, or rather of the tanks, are substantially flush with the undersurface of the hull 10. At the same time or thereafter, if necessary, the jacking mechanisms 26 are operated to lower or raise the caissons 24 until their lower ends are substantially flush with the undersurface of the hull 10. Thereupon, the entire structure will be in condition to be towed to another marine location.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiment has been shown and described only for the purpose of illustrating the principles of this invention and is subject to extensive change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

I claim:

1. In a mobile offshore marine platform for erection at marine sites of predetermined water depth and includingz-a platform-like, buoyant body; openwork towers. for.

stably supporting the body on the marine bottom at a selected marine site, the towers being of greater height than the water depth at the Site and guide means on the body mounting the towers for vertical movement relative to the body, the combination comprising: controllable-buoyancy tank means secured to the lower end of each of the towers for selectively floating each tower in a position wherein the major portion of its length is above water or sinking each tower to any selected depth between said position and a position wherein the tower engages the marine bottom; a set of elongated upright supporting members, of less height than the towers disposed uniformly about each of the latter, the length of said members being greater than the draft of said body; guide means on the body mounting said members for vertical movement relative to the body; means for detachably connecting the upper ends of the members of each of said sets with the upper end of the corresponding tower when said member and tower ends are on the same level; and power-operated means mounted on the body for selectively effecting or restraining said member movement in order to raise or lower said members relative to the body and in order to raise the body out of the water or lower the body back down to the water on said members when the latter are connected to the towers and the latter are engaged with the marine bottom, said power-operated means being separate from said members and mechanically engageable therewith.

2. The structure defined in claim 1 wherein the guide means for the towers comprise wells extending through the body and the tank means constitute extensions of References Cited in the file of this patent UNITED STATES PATENTS 131,746 DuBois Oct. 1, 1872 2,090,854 Timbs Aug. 24, 1937 2,210,408 Henry Aug. 6, 1940 2,334,992 Crake Nov. 23, 1943 2,352,370 Carruthers June 27, 1944 2,589,146 Samuelson Mar. 11, 1952 2,600,542 Jourdain June 17, 1952 2,771,747 Rechtin Nov. 27, 1956 2,833,118 Nixon May 6, 1958 2,892,314 Hornsby et a1 June 30, 1959 FOREIGN PATENTS 600,129 Great Britain Apr. 1, 1948 713,298 Great Britain 1954 OTHER REFERENCES Popular Science, p. 160, January 1956. 

